docs: def usage():
      """
          Prints usage message.
          """
  
      print('Usage:', os.path.basename(sys.argv[0]), '[options] dimacs-file')
      print('Options:')
      print('        -a, --adapt              Try to adapt (simplify) input formula')
      print('        -c, --comp=<string>      Enable one of the MSE18 configurations')
      print('                                 Available values: a, b, none (default = none)')
      print('        -e, --enum=<int>         Number of MaxSAT models to compute')
      print('                                 Available values: [1 .. INT_MAX], all (default = 1)')
      print('        -h, --help               Show this message')
      print('        -i, --incr               Use SAT solver incrementally (only for g3 and g4)')
      print('        -l, --blo                Use BLO and stratification')
      print('        -m, --minimize           Use a heuristic unsatisfiable core minimizer')
      print('        -s, --solver=<string>    SAT solver to use')
      print('                                 Available values: g3, g4, lgl, mcb, mcm, mpl, m22, mc, mgh (default = g3)')
      print('        -t, --trim=<int>         How many times to trim unsatisfiable cores')
      print('                                 Available values: [0 .. INT_MAX] (default = 0)')
      print('        -v, --verbose            Be verbose')
      print('        -x, --exhaust            Exhaust new unsatisfiable cores')